1package Sys::Hostname;
2
3use strict;
4
5use Carp;
6
7use Exporter 'import';
8
9our @EXPORT  = qw/ hostname /;
10
11our $VERSION;
12
13use warnings ();
14
15our $host;
16
17BEGIN {
18    $VERSION = '1.25';
19    {
20	local $SIG{__DIE__};
21	eval {
22	    require XSLoader;
23	    XSLoader::load();
24	};
25	warn $@ if $@;
26    }
27}
28
29
30sub hostname {
31  @_ and croak("hostname() does not accepts arguments (it used to silently discard any provided)");
32
33  # method 1 - we already know it
34  return $host if defined $host;
35
36  # method 1' - try to ask the system
37  $host = ghname() if defined &ghname;
38  return $host if defined $host;
39
40  if ($^O eq 'VMS') {
41
42    # method 2 - no sockets ==> return DECnet node name
43    eval { local $SIG{__DIE__}; $host = (gethostbyname('me'))[0] };
44    if ($@) { return $host = $ENV{'SYS$NODE'}; }
45
46    # method 3 - has someone else done the job already?  It's common for the
47    #    TCP/IP stack to advertise the hostname via a logical name.  (Are
48    #    there any other logicals which TCP/IP stacks use for the host name?)
49    $host = $ENV{'ARPANET_HOST_NAME'}  || $ENV{'INTERNET_HOST_NAME'} ||
50            $ENV{'MULTINET_HOST_NAME'} || $ENV{'UCX$INET_HOST'}      ||
51            $ENV{'TCPWARE_DOMAINNAME'} || $ENV{'NEWS_ADDRESS'};
52    return $host if $host;
53
54    # method 4 - does hostname happen to work?
55    my($rslt) = `hostname`;
56    if ($rslt !~ /IVVERB/) { ($host) = $rslt =~ /^(\S+)/; }
57    return $host if $host;
58
59    # rats!
60    $host = '';
61    croak "Cannot get host name of local machine";
62
63  }
64  elsif ($^O eq 'MSWin32') {
65    ($host) = gethostbyname('localhost');
66    chomp($host = `hostname 2> NUL`) unless defined $host;
67    return $host;
68  }
69  else {  # Unix
70    # is anyone going to make it here?
71
72    local $ENV{PATH} = '/usr/bin:/bin:/usr/sbin:/sbin'; # Paranoia.
73
74    # method 2 - syscall is preferred since it avoids tainting problems
75    # XXX: is it such a good idea to return hostname untainted?
76    eval {
77	local $SIG{__DIE__};
78	require "syscall.ph";
79	$host = "\0" x 65; ## preload scalar
80	syscall(&SYS_gethostname, $host, 65) == 0;
81    }
82
83    # method 2a - syscall using systeminfo instead of gethostname
84    #           -- needed on systems like Solaris
85    || eval {
86	local $SIG{__DIE__};
87	require "sys/syscall.ph";
88	require "sys/systeminfo.ph";
89	$host = "\0" x 65; ## preload scalar
90	syscall(&SYS_systeminfo, &SI_HOSTNAME, $host, 65) != -1;
91    }
92
93    # method 3 - trusty old hostname command
94    || eval {
95	local $SIG{__DIE__};
96	local $SIG{CHLD};
97	$host = `(hostname) 2>/dev/null`; # BSDish
98    }
99
100    # method 4 - use POSIX::uname(), which strictly can't be expected to be
101    # correct
102    || eval {
103	local $SIG{__DIE__};
104	require POSIX;
105	$host = (POSIX::uname())[1];
106    }
107
108    # method 5 - sysV uname command (may truncate)
109    || eval {
110	local $SIG{__DIE__};
111	$host = `uname -n 2>/dev/null`; ## sysVish
112    }
113
114    # bummer
115    || croak "Cannot get host name of local machine";
116
117    # remove garbage
118    $host =~ tr/\0\r\n//d;
119    $host;
120  }
121}
122
1231;
124
125__END__
126
127=head1 NAME
128
129Sys::Hostname - Try every conceivable way to get hostname
130
131=head1 SYNOPSIS
132
133    use Sys::Hostname;
134    my $host = hostname;
135
136=head1 DESCRIPTION
137
138Attempts several methods of getting the system hostname and
139then caches the result.  It tries the first available of the C
140library's gethostname(), C<`$Config{aphostname}`>, uname(2),
141C<syscall(SYS_gethostname)>, C<`hostname`>, C<`uname -n`>,
142and the file F</com/host>.  If all that fails it C<croak>s.
143
144All NULs, returns, and newlines are removed from the result.
145
146=head1 AUTHOR
147
148David Sundstrom E<lt>F<sunds@asictest.sc.ti.com>E<gt>
149
150Texas Instruments
151
152XS code added by Greg Bacon E<lt>F<gbacon@cs.uah.edu>E<gt>
153
154=cut
155
156